For reasons of aesthetics and architectural design, flush fire protection sprinklers are designed so that only the thermally responsive element is exposed within the room. The rest of the structure is hidden above the ceiling (pendant-type flush fire protection sprinklers) or behind the wall (horizontal sidewall-type flush fire protection sprinklers). When the sprinkler is actuated, a deflector, hidden from view in the standby condition of the fire protection sprinkler, moves from a retracted position to an extended, fixed condition within the room to deflect water flowing from the sprinkler orifice over the area to be protected.